Method and apparatus for coating filaments



Nov. 2, 1954 A, c. RADTKE ET AL 2,693,429

METHOD AND APPARATUS FOR COATING FILAMENTS Filed June a, 1950 2 Sheeis-Sheet 1 I INVENTORS delzrz' C ad 6 FIG 5 4 P k N 1954 A. c. RADTKE ETAL 2,693,429

METHOD AND APPARATUS FOR COATING FILAMENTS Filed June 3, 1950 2 Sheets-Sheet 2 INVENTORS Melba! cpa q a9 BY Edji' I15 4 dhzmrwrmm United States Patent METHOD AND APPARATUS FOR COATING FILAMENTS Application June 3, 1950, Serial No. 166,002

17 Claims. c1. 117 -111 The present invention relates to improved method and means for treating filamentous material and more particularly to applying a coating to filaments or strands of such material, especially glass fibers.

In the production of glass filaments and strands of the continuous textile type, it is usually desirable to apply a suitable lubricant or binder to the newlyv formed filaments as they are gathered into a strand. Newly formed bare glass filaments readily abrade one another to the extent that the filaments are weakened or broken unless preventive measures are taken. The application of a lubricant or binder to the filaments before they are brought into contact with one another overcomes the tendency to abrade one another and provides suflicient strand integrity to permit handling during subsequent textile operations. Usually such lubricants or binders are light mineral or vegetable oil emulsions and may contain a starch or other adhesion promoting components when greater binding characteristics are desired. The binder may also contain resinous materials suitable for subsequent fabricating operations.

. Maximum tensile strength and knot strength in the finished strand are obtained by coating the fibers as they 'are produced with molten coating materials. It has been found that the strength of strands of glass filaments may be substantially increased by applying a coating to the newly formed filaments before the fibers are gathered into a strand.

T It is a primary 'object of the present invention to provide a novel apparatus for applying a coating material in a molten state to newly formed glass filaments thereby increasing the tensile strength of strands of the 1 filaments.

Another object of the invention is the provision of means for controlling the temperature of the coating material.

A further object of the invention is to provide in a filament coating apparatus means for precisely regulating the amount of material applied to the filaments. A still further object of the invention is to provide an efiicient apparatus for economically applying a coating to continuously moving filament or strand materials. A still further object of the invention is the provision of an etficient method for applying a coating material in a molten state to glass fiberstrands or filaments. Other objects and advantages of the invention will become apparent during the course of the following del scription.

The present invention provides apparatus to apply coating materials such as waxes andresins to newly formed glass filaments, the materials being applied in a molten state to the filaments as they are attenuated. An embodiment of the invention is illustrated in the acoompanying drawings, in which:

Figure 1 is a diagrammatic side elevational view of a typical glass filament forming apparatus shown in con nection with the present invention;

Figure 2 is a front elevational view of the applicator unit of the invention;

Figure 3 is a vertical sectional view through the applicator taken substantially on the' line 3-3 of Figure 2; "Figure 4 is a detail sectional view taken on the line 4'4 of Figure 1; and

Figure 5 is a detail sectional view of a modified form'of the invention."

Referring now to the drawings and Figure l in particular, theinvention is shown in connectionwith apparatus insulation 23.

r 2,693,429 Patented Nov. 2, 1954 ice for forming continuous type textile glass filaments. This apparatus includes a feeder 10 adapted to contain a supply of molten glass and is provided in its bottom wall with a plurality of discharge tips 11 from which the glass flows in the form of molten streams 12. The streams are gathered together into a bundle at a gathering pad 13 to form a strand 14. A lubricant or binder for the filaments is usually applied to the strand at the pad 13. Attenuation of the streams to fine filaments is effected by winding the strand on a rapidly rotating spool S or drum. The winding speed may be at the rate of 5,000 to 10,000 feet per minute or more. Winding the strand on the spool not only attenuates the streams 12 to fine filaments but collects the attenuated strand ino a package of suitable size for further processing. While the foregoing represents one form of apparatus for producing continuous type glass filaments, it will be readily understood that the present invention may be successfully employed in other filamerit forming processes.

It has been found that the strength of the strands of glass filaments may be improved by properly treating the filaments as they are formed. Under normal operating conditions, the molten glass in the streams cools rapidly as the streams are attenuated and coating materials applied to cold filaments or strands do not always result in completely covering the filaments or impregnation of the strand.

In order to preserve the high filament strength and reduce the tendency of the filaments to abrade one another, the present invention contemplates applying a coating to the filaments while the glass is still at an elevated temperature. Suitable coating materials may include waxes, bitumens, rosins, synthetic resins, and mixtures thereof. For example, the waxes may include cerese wax, mineral waxes, parafiin wax, microcrystalline Wax, carnauba wax, Japan wax, vegetable waxes, beeswax, or the like, or mixtures thereof. Typical examples of suitable resins for use in coating the filaments are polyvinyl acetate, polyvinyl chloride, or copolymers thereof, methyl methacrylate, phenol formaldehyde, urea formaldehyde, polyester resins, and other conventional thermoplastic and thermosetting synthetic resins.

The above noted materials are all applied to the filaments in a molten state in order that the viscosity of the material may be such that the rapidly moving filaments may be completely coated. The waxes normally have a melting point of from F. to 190 F. with a preferred melting temperature in the range of F. to F. although variations from this range are permissible. The important properties of the waxes are preferably plasticity, softness, and freedom from tackiness at room temperature. The temperature at which the resins, rosin, and bituminous materials are applied is dependent primarily upon the characteristics of the materials and the viscosity at which the material can be most efiiciently applied.

The accompanying drawings illustrate one form of apparatus for applying coating material in a molten state to strand materials such as glass fibers or filaments. The apparatus comprises generally a casing 15 forming a receptacle for a body of coating material 16 and comprising a housing for an applicator roll assembly 17. The casing 15 is preferably rectangular in cross-section and is provided with an inner receptacle 19 formed of sheet metal and having a vertically extending partition 20 dividing the receptacle into melting and delivery zones or chambers 21 and 22 respectively. The inner receptacle 19 is spaced from the Walls of the casing 15 by suitable Insulated covers 24 and 25 are hingedly connected to the casing 15 and cover respectively the melting and delivery zones. A melting basket 26 in the form of a perforate screen is provided in the melting chamber and the cold or unmelted material is placed therein. The basket prevents the circulation of unmelted particles into the delivery chamber.

' Heating means 27 are provided beneath the melting zone 21 and additional heating means 28 are provided beneath the delivery zone 22. These heating units may be resistance type heaters such as those known as Calrod units and are supported within an air space 29. The heating units 27 and 28 are preferably separately controlled to regulate the temperature within the respective zones. The temperature within the melting zone 21 is preferably maintained only high enough to reduce the viscosity of the materialsufficiently so that it will flow into the delivery zone. This prevents overheating the material and, in the case of some resins, prevents unduly increasing the degree of polymerization. The heating units 28 increase the temperature of the softened or fluid material to the degree necessary to permit readily transferring it to the applicator roll.

Insulation 30 adjacent the partition 20 serves to prevent more than a minimum transfer of heat between the chambers 21 and 22. A drain plug 31 is provided for removing unused material and cleaning the receptacle.

The applicator roll assembly 17 includes a transfer roll 32 journaled in bearing blocks 33 supported on the casing in slideways 34 for easy removal from the casing. Rotation is imparted to the roll by means of an electric motor 35 and suitable gearing 36 shown in Figure 2. The transfer roll 32 is rotated in a counterclockwise direction and is positioned so as to dipslightly below the surface of the body of molten coating material 16 in the delivery zone. film of the coating material upwardly for transfer to an applicator roll 38 which transfers the coating carried thereby to the filaments 12. The applicator roll 38 is journaled in slide blocks 39 mounted in the slideways 34 secured to the casing 15. The'roll 38 is driven by surface contact with the transfer roll 32 and is held in contact therewith by means of spring tension members 41 trained about grooved collars 42 carried by the bearing blocks.

The applicator roll is so positioned with respect to the feeder 10 and the gathering pad 13 that the filaments extend in a row across the roll and are drawn over the roll in light and substantially tangential contact with the surface of the roll. Normallythe filaments travel at speeds'in the neighborhood of from 5,000 to 10,000 feet or more per minute while the applicator roll may have a surface speed of about to 50 feet a minute. Preferably the roll is rotated in such direction that its surface where it contacts the filaments moves in the same direction as the filaments/ Due to the enormous difference in speed between the roll and the filaments, the coating material is picked up from the rollby a wiping action of the filaments thereover.

Referring particularly to Figure 4 of the drawings, it will be noted that the applicator roll 38 is provided with a section of reduced diameter 45 thereby providing a shoulder 46 adjacent the contacting surfaces of the rolls 32 and 38. This difference in diameter of the applicator roll may be only a few thousandths of an inch, say from .003 to .015 inch, and'this regulates the thickness and amount of the coating material to be transferred to the filaments. The tension on the spring members 41 connecting the two rolls tends to maintain a substantially uniform thickness of the coating material although it will be apparent that the ends of the applicator roll may at times be forced slightly apart by coating material at the ends of the transfer rolls. The amount of coating material delivered by the applicator roll is also partially controlled by the temperature of the material in the delivery zone. r

Most organic substances such as the aforementione waxes and resinous materials tend to decompose at temperatures above 500 F. so that it becomes necessary to maintain the coating material well below the temperature of decomposition, say at 350 F. or so. At this temperature, however, the coating material may have too great a cooling effect on the hot glass filaments to which is is applied and the viscosity of the material may be so high that it causes too great a drag on the filaments passing over the roll.

By the present invention, the coating material is maintained at a moderate temperature and is only temporarily and for a short time raised to the high-application temperature. The material is held at the highest temperature only while being transferred to the filaments. This is accomplished by providing heating elements 48 arranged in the hinged cover and so disposed in relation to the roll 38 that the heat from the elements is transferred directly to the surface of the roll. vThis zone of high heat is effective only for suddenly increasing 'Rotation of the roll carries a the temperature of the coating material at the instant before it is applied to the filaments. The highly heated coating is picked up from the roll by the filaments passing thereover and rotation of the applicator roll carries into contact with the cooler material on the transfer roll 32 any coating material not picked up by the filaments and remaining on the applicator roll. This action reduces the tendency of the coating material on the applicator roll to char or otherwise decompose.

As illustrated in Figure 2 of the drawings, the filaments or streams of molten glass take the form substantially of a fan so that the filaments are in contact with the applicator roll at various angles. The angle of contact of the majority of the filaments affects to some extent the amount of coating material picked up thereby. The length of the fan may be adjusted by raising or lowering the gathering pad 13 to vary the angle of contact of the filaments with the roll. Reducing the length of the fan decreases the angle of contact of the filaments with the roll so that a greater amount of coating material is transferred to the filaments especially at the edges of the fan. When the filaments are gathered together the coatings on the filaments tend to coalesce and form a substantially continuous body of coating material in which the filaments are all encased and by which they are all bonded together.

Figure 5" illustrates a modified means for heating the applicator roll 38. Heating elements 50 such as Calrod units may be embedded in suitable number in the roll 38 near the surface thereof. Current is supplied to the rods 50 through contact rings 51 mounted on the end 52 of the roll supporting shaft and connected by lead wires 53 to the rods.. Brush contacts 54 bearing on the rings 51 provide connection with a suitable source of current.

At the start of the operation, attenuation of the streams of molten glass is commenced by gathering the streams together at the pad and starting the strand on the winding spool. Water or other fluid may be fed to the strand at the pad as a temporary lubricant until the winder reaches fullattenuating speed. The roll applicator is then brought into contact with the fan of filaments after which the water or other lubricant may be shut off.

In the operation of the apparatus, a mass of coating material, either solid or in molten state, is fed intothe screened section of the melting chamber 21 until the desired level is reached. Heatis supplied by the units 27 to reduce the material to a fluid state if such material is in solid form when cold or to lower the viscosity of materials which are already fluid. The temperature in the melting chamber is normally maintained at about the melting temperature of the coating material or only sufiiciently high to assure a flow of material into the delivery zone or chamber 22.

The heating elements 28 in the zone 22 increase the temperatureof the fluid within a localized area to further decrease the. viscosity to the point where only a thin film of the material is picked up by the transfer roll 32. The coating material in the delivery zone is purposely maintained at a low volume so that only a minimum amount is heated to the higher temperature. This is particularly advantageous when heat polymerizable resins are employed since the more highly heated material is rapidly removed by the transfer roll 32 before any unwanted curing is effected. The film-like coating on the transfer roll 32 feeds material to the surface of the applicator roll 38 in amounts to fill the recessed portion thereof. The roll 38 rotates in a clockwise direction when viewed as in Figure 3 and carries the film of coating material into tangential contact with the fan of filaments 12. The filaments traveling at a high rate'of speed wipe the material from the roll, thus completely covering the filaments in a continuous sheath. As the filaments are brought together at the gathering pad, the coatings on the filaments combine or coalesce to form a continuous body about the strand.

The coating apparatus is preferably placed in close relation to the source of the streams of glass in order that the filaments may be coated while still at a high temperature. Bringing the hot filaments into contact with a comparatively cold coatingcompound may undesirably cool the filaments. This is overcome by providing heating elements 48 in the eover 25 which direct intense heat against the roll surface immediately adjacent the point of contact with the filaments or by heating the roll as shown in Figure This quickly ralses the temperature of the coatiig material substantially to the point of decomposition. The superheating interval is of such short duration and the material cools at such a rapid rate that no ill effects result. It has been found that the temperature of the superheated coating and the glass filaments at the point of contact with the roll are substantially uniform so that the coating readily covers thefilaments without chilling effect. Thus the coating and filament cool uniformly which tends to promote a good adhesion between the coating material and the new bare glass surface.

As an example, paratfin wax, having a melting point of 1 F. to 150 F., is placed in the melting chamber a 21 where the temperature is maintained in the neighborhood of say 175 F. to assure complete melting of the wax. The fluid wax then flows into the delivery chamber 22 where the temperature is raised to 180 F. to 225 F. to further reduce the viscosity and permit a thin film of fluid to adhere to the transfer roll 32. The material transferred to the applicator roll 38 may then be heated to 300 F. or more before it is discharged onto the filaments. By this method it is unnecessary to mamtain the entire body of coating material at a temperature approaching the degree where decomposition or volatilization will take place.

The temperature in the several zones may, of course, be varied according to the type of material and the speed of the rolls may also be regulated to control the amount of material transferred to the filaments.

We claim:

1. Apparatus for coating filamentous material comprising a receptacle adapted to contain a supply of coating material and divided into melting and delivering zones, means for heating said receptacle, an applicator roll journally supported in said delivery zone, means engaging the material in the delivery zone for transferring the coating material to said roll, means for continuously rotating the roll, means for heating said roll, and means for establishing a film of coating material on the roll for transferring a predetermined amount of said coating material from said applicator roll to filaments to be coated.

2. Apparatus for coating heated filaments comprising a receptacle adapted to contain a supply of coating material and divided into melting and delivery zones, means for independently heating said zones at different temperatures, an applicator roll for transferring the coating material from the delivery zone to filaments to be coated, and means for heating said roll to elevate the temperature of the coating material approachingthe temperature of the filaments at the zone of application of the material to the filaments- 3. Apparatus for coating filamentous material comprising a receptacle adapted to contain a supply of coating material in a molten state and divided into melting and delivery zones, means for independently heating the material in said zones at different temperatures, an applicator roll, means for transferring the coating material to said roll, means for continuously rotating said transferring means, and means for heating said applicator roll to a temperature above the temperature of the material in said delivery zone.

4. Apparatus for applying a coating material in a molten state to filamentous material comprising a receptacle adapted to contain a supply of coating material and divided into melting, transferring and discharging zones, means for progressively and independently heating the material in said zones, and an applicator roll at the material discharging zone adapted to transfer the coating material from the zone of highest temperature to the filamentous material to be coated.

5. Apparatus for applying a coating material in a molten state to newly formed hot glass filaments comprising a receptacle adapted to contain a supply of coating material, means dividing said receptacle into melting and delivery zones, means for heating said melting zone, means for heating said delivery zone to an increased temperature, an applicator roll, a transfer roll contacting the coating material in said delivery zone for transferring the coating material to said applicator roll, means for driving said rolls, and means for heating the surface of said applicator roll to a temperature approaching the temperature of the glass filaments to be coated.

6. Apparatus for applying molten coating material to newly formed hot glass filaments comprising a recep: tacle adapted to contain a supply of coating material, means dividing said receptacle into melting and delivery chambers, a basket having perforate Walls disposed in said melting chamber adapted to receive solid coating material to be melted, means for independently heating said chambers at different temperatures, an applicator roll, means within the delivery chamber for transferring the coating material to said applicator roll, and means for heating the surface of said applicator roll to a temperature higher than that of the melting and delivery chambers.

7. Apparatus for applying molten coating material to newly formed glass filaments comprising a receptacle adapted to contain a supply of melted coating material, means dividing said container into melting and delivery chambers, means for supplying heat to said melting chamber, means for increasing the temperature of the material in said delivery chamber, an applicator roll, a transfer roll within the delivery chamber for transferring the coating material to said applicator roll, means for continuously driving said rolls, means for predetermining the amount of coating material applied to said filaments by the applicator roll, and means for heating the surface of said applicator roll to a temperature higher than the temperatures of said melting and delivery chambers.

8. The method of coating filamentous material which comprises the steps of establishing a supply body of coating material, flowing said body of material successively through a plurality of zones, independently heating said zones, transferring said coating material from said supply body to. a point of discharge, applying said coating to filaments passing said point of discharge, and increasing the temperature of said material at the point of discharge prior to discharging the material onto said filaments.

9. The method of coating filamentous material which comprises the steps of establishing a supply body of coating material in a molten state, flowing said body through a plurality of zones heated to progressively increased temperatures, transferring said coating material in a predetermined amount from said supply body to a point of discharge, applying said coating to filaments passing said point of discharge, and increasing the temperature of said material at the point of discharge prior to discharging the material onto said filaments.

10. The method of coating filaments which comprises the steps of establishing a supply body of coating material, heating the coating material, flowing the material to a zone of application, increasing the temperature of the material, conveying the heated material to an applying station, still further increasing the temperature of the material, and transferring the heated material from the applying station to filaments to be coated.

11. The method of coating glass filaments with a heat-softenable coating material which comprises the steps of establishing a supply body of coating material, flowing said material through a plurality of zones, applying melting temperature to the coating material in one of said zones, increasing the temperature of the material in the succeeding zone, transferring said heated coating material as a film from said supply body to a point of discharge, transferring said coating by rolling contact onto filaments passing said point of discharge, and further increasing the temperature of said material to a temperature approaching that of the glass filaments at the point of discharge prior to discharging the material onto said filaments.

l2. The method of coating hot newly formed glass fibers which comprises establishing a supply body of coating material in a molten state, flowing said material through melting, transferring and delivering zones, independently heating said zones to progressively increased temperatures, transferring said coating material as a film from said transfer zone to said deliverv zone, transferring said film of coating to filaments passing said delivery zone, and increasing the temperature of said material at the delivery zone to a temperature approximating that of the hot filaments prior to discharging the material onto said filaments.

13. The method of coating hot glass filaments which comprises maintaining a heated supply body of coating material, heating a portion of said material to filmforming viscosity, transferring a film of said coating material from said supply body to a point of discharge, applying said coating as a film-like sheath to filaments passing said point of discharge, and increasing the temperature of said film of material at the point of discharge prior to discharging the material onto said filaments.

14. The method of coating heated filaments which comprises establishing a supply body of coating material, flowing the material through a plurality of independently heated zones of difierent temperatures, transferring said coating material in the form of a film from said supply body to a point of discharge, transferring said film of coating material by rolling contact onto filaments passing said point of discharge, and increasing the temperature of said film of material to a temperature approaching that of the filaments at the point of discharge prior to discharging the material onto said filaments.

15. The method of coating hot glass filaments which comprises establishing a supply body of coating material, flowing said body through melting, delivery and discharge zones, individually heating said zones to progressively higher temperatures, transferring said coating to each said zone in succession, and discharging said coating onto filaments passing a point of discharge, the temperature of said material and said filaments being substantially uniform at the point of discharge.

16. The method of coating hot glass filaments by applying to the filaments as they are formed a filmlike sheath of heated coating material which comprises maintaining a supply of said material in a molten state, heating a portion of the material to film-forming viscosity, removing a film of material therefrom and finally raising the temperature of said film to substantially equal the temperature of said hot glass filaments, and bringing said film of material into contact with said filaments to coat the filaments.

17. Apparatus for coating hot glass filaments with a film-like sheath of heated coating material comprising an insulated receptacle adapted to contain a supply of said coating material in a molten state, means for heating a portion of said supply body of material to filmforming viscosity, a transfer roller in substantially surface contact with said heated body of material, means for rotating said roller to carry a film of material away from said body, a second roller having frictional driving contact with said transfer roller adapted to receive the film of material carried thereby and discharge it onto the filaments to be coated, and heating means associated with said second roller to heat said film to a substantially increased temperature approaching that of the glass filaments.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 1,312,567 Ordway Aug. 12, 1919 1,961,829 Rutkoskie June 5, 1934 2,011,615 Choice et al. Aug. 20, 1935 2,117,200 Miller May 10, 1938 2,144,924 King Jan. 24, 1939 2,181,690 Boyd Nov. 28, 1939 2,272,588 Simison Feb. 10, 1942 2,315,259 Hyde Mar. 30, 1943 2,331,980 Hoffman Oct- 19, 1943 2,396,946 Gruppe Mar. 19, 1946 2,468,266 Lyons et a1. Apr. 26, 1949 

1. APPARATUS FOR COATING FILAMENTOUS MATERIAL COMPRISING A RECEPTACLE ADATED TO CONTAIN A SUPPLY OF COATING MATERIAL AND DIVIDED INTO MELTING AND DELIVERING ZONES, MEANS FOR HEATING SAID RECEPTACLE, AN APPLICATOR ROLL JOURNALLY SUPPORTED IN SAID DELIVERY ZONE, MEANS ENGAGING THE MATERIAL IN THE DELIVERY ZONE FOR TRANSFERRING THE COATING MATERIAL TO SAID ROLL. MEANS FOR CONTINUOUSLY ROTATING THE ROLL, MEANS FOR HEATING SAID ROLL, AND MEANS FOR ESTABLISHING A FILM OF COATING MATERIAL ON THE ROLL OF TRANSFERRING A PREDETERMINED AMOUNT OF SAID COATING MATERIAL FROM SAID APPLICATOR ROLL TO FILAMENTS TO BE COATED.
 8. THE METHOD OF COATING FILAMENTOUS MATERIAL WHICH COMPRISES THE STEPS OF ESTABLISHING A SUPPLY BODY OF COATING MATERIAL, FLOWING SAID BODY OF MATERIAL SUCCESSIVELY THROUGH A PLURALITY OF ZONES, INDEPENDENTLY HEATING SAID ZONES, TRANSFERRING SAID COATING MATERIAL FROM SAID SUPPLY BODY TO A POINT OF DISCHARGE, APPLYING SAID COATING TO FILAMENTS PASSING SAID POINT OF DISCHARGE, AND INCREASING THE TEMPERATURE OF SAID MATERIAL AT THE POINT OF DISCHARGE PRIOR TO DISCHARGING THE MATERIAL ONTO SAID FILAMENTS. 